Carb Troubles Autolite 1100

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AlicePyeHole
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Carb Troubles Autolite 1100

Post by AlicePyeHole »

Hi friends!
Long time listener, first time caller.

I'm having some issues with my carb. I have a 1963 F100 with a 223 I6 engine with a manual 3 speed transmission and the carb I have on there is an Autolite 1100 which (after some googling) I've decided probably came from a 1964 Galaxie. (The number on the carb reads C4TFE, but I'm assuming it's the same as the C3AFA)

I'm having an issue trying to get it to idle right. I can't seem to open the choke completely unless the idle speed is set really high, and I can't get it to idle at all at 475 rpm, which is what the book says it should be at. At first we thought that the idle circuit might be clogged so we rebuilt it and cleaned every little hole in it. I've tried checking for vacuum leaks, which is what it kind of feels like at times, but there doesn't seem to be one. Everything on the ignition side of things is new and works great, timing was also checked and looked good. So my last idea is that I have the wrong main jet size on there. I just took it out and it looks like its .065. Does that seem right? I'm thinking it's too large maybe?

Has anyone had any similar experiences with these carbs? Any ideas of other things I should check? What would be your best guess for main jet size on this thing?

Thanks everyone!
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ThinLizzy13
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Re: Carb Troubles Autolite 1100

Post by ThinLizzy13 »

Pull the carb off. If you can wiggle the throttle shaft at all then it needs to be rebuilt. Worn throttle shafts seem to be a common issue. I just went through almost exactly what you are right now :2cents:

Edit: just wanted to add that the jet size you mentioned is fine. That’s the size I have on my carbs for my 223.
'63 F100 223 3OT
‘20 F150 XL
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AlicePyeHole
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Re: Carb Troubles Autolite 1100

Post by AlicePyeHole »

We checked the throttle shaft, and we thought it was okay!

The spark plugs are real black so I think I am running it very very rich. The other thing is that makes me think it's the jet size is that when I bottom out the idle mix screw while the engine is running I'd doesn't die, which is strange I think.

Gonna try a bunch of main jet sizes today, which me luck! 8)
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ThinLizzy13
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Re: Carb Troubles Autolite 1100

Post by ThinLizzy13 »

AlicePyeHole wrote: when I bottom out the idle mix screw while the engine is running I'd doesn't die, which is strange I think.
By bottom out do you mean all the way in or all the way out? Is the end of the screw deformed at all?
Also does your autolite have the vent valve rod on top? If that is not set correctly the engine won’t idle at the specified RPM.
'63 F100 223 3OT
‘20 F150 XL
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Jason_S
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Re: Carb Troubles Autolite 1100

Post by Jason_S »

I'm not real good with diagnosis over the computer, but throwing a few things at you...
the carb I have on there is an Autolite 1100 which (after some googling) I've decided probably came from a 1964 Galaxie. (The number on the carb reads C4TFE, but I'm assuming it's the same as the C3AFA)
The 1100 was used on a lot of FoMoCo cars and trucks through the 60's, so the basic carb kit is the same for many carb numbers.

From the '64 Ford Truck shop manual, C4TF-E is shown for a 64 F-100 thru 350 w/ 262 and manual transmission. Venturi diameter is listed as 1.200 inches with a 1 9/16" throttle bore diameter.

The 65F jet shows to be the jet for 5,000 - 10,000 ft elevation on the C4TF-E carb and the C3TF-U,V &Y (223 carbs). A 67F jet is listed for 0-5,000 ft elevation.

The idle mixture screw should be turned in until seated and then backed out 1 1/2 turns.

Specs from the '64 book have 525-550 rpm for a 223 and 262 with a manual.
I've tried checking for vacuum leaks, which is what it kind of feels like at times, but there doesn't seem to be one.


If the idle mixture screw doesn't affect anything and you have to choke the carb for it to run, then it sure sounds like there is a vacuum leak from somewhere.

Is this a recent occurrence since going through the carb?

For the 1100 on my '64, whenever I rebuild the carb I use a very thin layer of Permatex #2 on the gasket between the top of the carb and the body as well as between the intake and the carb. At some point in the past, the screws on the carb top had been overtorqued and gave the top a slight deformation at the screw holes. The sealer helps seal off any potential vacuum leaks at the venturi area and the carb to intake manifold.

As for the carb to intake mounting, torquing the nut closest to the intake can be troublesome for me. A box end crows foot or similar can help get it torqued down properly. I made one out of a cheap box end welded to some square tubing.

Another place to check is the vacuum diaphragm at the distributor. If the diaphragm has a tear or hole, it could cause a vacuum leak. A leak may also occur at the gasket on the spark control valve on the side of the carburetor.

Also, unsure if there is a PCV on your truck. If so, check the connection to the intake manifold, the hose and the PCV grommet for leaks.

Let us know what you find...
"1) Peace through strength; 2) Trust but verify; 3) Beware of evil in the modern world"

1964 F-100, 223/3-spd
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bruceandersson
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Re: Carb Troubles Autolite 1100

Post by bruceandersson »

I wonder if your float is too high. That could provide excess gas at all time, but also allow the idle mixture screw to have no real effect.
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AlicePyeHole
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Re: Carb Troubles Autolite 1100

Post by AlicePyeHole »

Checked for vacuum leaks multiple times by spraying carb cleaner all around to see if the rpm goes up, but it didn't seem to.
Tried different jet sizes, going smaller seemed to help at first, but I still can't get it to idle with the choke open.
I've taken the carb apart and cleaned it several times now.
We've set the float properly. The distributor is new and I don't think that where the problem is.
I've given up at this point and purchased a new carburetor. It comes in tomorrow, so I'll try to update y'all then!
Thanks so much for all your help so far, everyone!
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ThinLizzy13
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Re: Carb Troubles Autolite 1100

Post by ThinLizzy13 »

Did your new carb do the trick?
'63 F100 223 3OT
‘20 F150 XL
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